In general, a method for detecting a staying point by analyzing trace data based on history of Global Positioning System (GPS) data recorded by a device such as a GPS logger has been developed. Such method is disclosed in Japanese Laid-open Patent Publication No. 2011-154004 and Non-Patent Literatures 1 to 3, for example. Non-Patent Literature 1 is Yu Zheng, Lizhu Zhang, Xing Xie, Wei-Ying Ma, “Mining Interesting Locations and Travel Sequences from GPS Trajectories”, WWW 2009, pp. 791 to 800. Non-Patent Literature 2 is Zheng Huo, Xiaofeng Meng, Haibo Hu, Yi Huang, “You Can Walk Alone: Trajectory Privacy-preserving through Significant Stays Protection”, DASFAA (1) 2012, pp. 351 to 366. Non-Patent Literature 3 is Y. Zhu, Y. Zheng, L. Zhang, D. Santani, X. Xie, and Q. Yang, “Inferring Taxi Status Using GPS Trajectories”, November 2011, Technical Report MSR-TR-2011-144.